1. Field of the Invention
The present invention relates to a digital piano apparatus that mixes multiple tone signals corresponding to input signals from multiple keys and pedals to output a sound from speakers, a method for synthesis of sound fields for a digital piano, and a program for synthesis of sound fields for a digital piano.
2. Description of the Related Art
In a typical common stereo digital piano in related art, a sound image is reproduced so as to draw a semicircle upward from the ends of two speakers toward the midpoint of the two speakers. Accordingly, a listener of the stereo digital piano in the related art can listen to the reproduced stereo sound image well if he/she is located near the midpoint of the two speakers.
Digital piano systems are provided in which speakers serving as sound sources are physically arranged in piano-shaped (grand piano-shaped) cases. In such a digital piano system, since the speakers arranged in the piano-shaped (grand piano-shaped) case serve as sound sources, a listener of the digital piano system can listen to a sound image reproduced inside the case of the digital piano system well.
Methods of reproducing sounds in virtual three-dimensional spaces are also proposed. In such a sound reproducing method in a virtual three-dimensional space, multiple acoustic vectors are set, a virtual space is formed by the boundaries of a polygon, and propagation historical data concerning the acoustic vectors for a predetermined time duration in which sound waves that are reflected from the boundaries are propagated is calculated and stored.
In the sound reproducing method in a virtual three-dimensional space, transient responses reaching measurement points, which are small surface elements of the sound waves reflected from the boundaries and velocity potentials to the measurement points on the basis of the propagation historical data, the transient responses are added to numeric arrays in time series, and the added results are stored. Accordingly, the sound reproducing method in a virtual three-dimensional space can use an approximate boundary integral method to yield precise acoustic characteristics of a space including a wide frequency band in a relatively short time even with an inexpensive computer (refer to Japanese Unexamined Patent Application Publication No. H8-272380).